Chemical mechanical planarization (“CMP”) polishing compositions (CMP slurries, CMP composition or CMP formulations are used interchangeably) are used in the production of a semiconductor device. The present invention relates to polishing compositions comprising refined composite particles (used as abrasive particles) that are especially suitable for polishing patterned semiconductor wafers that comprise silicon oxide materials.
Silicon oxide is widely used as dielectric materials in semiconductor industry. There are several CMP steps in integrated circuit (IC) manufacturing process, such as shallow trench isolation (STI), inter-layer dielectric (ILD) CMP and gate poly CMP etc. Typical oxide CMP slurry involves: abrasive, with or without other chemicals. Other chemicals could be dispersants to improve slurry stability, boosters to increase removal rate, or inhibitors to decrease removal rate and to stop on the other film, for example, SiN for STI application.
Desirable characteristics for a CMP slurry at advanced semiconductor technology nodes are reduced defects, high removal rates, very low with wafer non uniformity (WWNU) for removal rates and low topography. Having a very low WWNU for removal rates is particularly important. A higher non-uniformity would lead to over-polish in the regions on the wafers where removal rates and under-polish where least material is removed. This would create uneven topography on the wafer surface which is undesirable in semiconductor manufacturing. Therefore, considerable CMP process development is required in terms of pads, conditioning, polishing zone pressure adjustments to yield desired uniform removal rate profile.
Among common abrasives used in CMP slurries, such as silica, alumina, zirconia, titania and so on, ceria is well-known for its high reactivity toward silica oxide and is widely used in STI CMP slurry for the highest oxide removal rate (RR) due to the high reactivity of ceria to silica.
Cook et al. (Lee M. Cook, Journal of Non-Crystalline Solids 120 (1990) 152-171) proposed a ‘chemical tooth’ mechanism to explain this extraordinary property of ceria. According to this mechanism, when ceria particles are pressed onto silicon oxide film, ceria breaks down silica bonds, forms a Ce—O—Si structure and thus cleavage silica from the surface.
Most of the ceria used in CMP industry are manufactured from calcinations-wet milling process. The resulted ceria has sharp edges and very wide size distribution. It also has very large “large particle count” (LPC). All of these are believed to be responsible for defects and low yields, especially scratch after the wafer is polished. Different forms of ceria containing particles such as colloidal ceria or ceria coated silica particles are also being considered to resolve these challenging issues.
Ceria coated silica particles have been found especially useful for achieving high removal rates of silicon oxide films with lower defectivity (PCT/US16/12993). Yet the need exists still to further improve the removal rates, control the removal rate within-wafer-non-uniformity (WWNU) and reduce polishing defects.
The present invention relates to refined agglomerated composite particles, methods of refinement and method of using the refined composite particles in polishing applications that can achieve the performance requirements.
Therefore, there are significant needs for CMP compositions, methods, and systems that can offer excellent within wafer non-uniformity for removal rates and higher removal rates and low defects.